The purpose of this investigation will be to examine age differences in perception with respect to stimulus persistence theory. This theory suggests that neural representations of a stimulus persist in the nervous system for longer durations in the elderly than the young and that this has consequences for perception. Although empirical evidence for age differences in the persistence of stimuli has been limited, the data of visual masking studies appear to support the theory. The phenomenon of visual masking refers to a rise in the perceptual threshold of one stimulus due to the presentation of another stimulus. Recent investigations of backward masking, in which a target stimulus (TS) precedes a masking stimulus (MS), have indicated an increased susceptibility to the masking effect on the part of elderly individuals. This may represent an age-related decrease in the rate at which stimuli can be "cleared through" the nervous system. Evidence from more varied contexts is required, however. The present program will examine this age change in susceptibility to masking through the use of an alternative visual masking paradigm, that of forward masking, in which the MS precedes the TS. The effects of age as well as MS duration, MS luminance, and interstimulus interval, will be investigated. Conclusions drawn should contribute to an understanding of the concept of age-related increases in the nervous system's "clearing time" and will have bearing on investigations of perceptual functioning in elderly individuals.